Field of the Invention and Description of the Prior Art
This invention has reference primarily but not exclusively to character recognition devices and more particularly to such character recognition devices which are utilized to recognize characters as the characters are written by hand.
Thus, there is described in British Patent Specification No. 868431 apparatus for automatically recording hand written characters, comprising a support surface and an electrical control circuit activated by changes in direction of a writing instrument as it moves over the supporting surface.
Furthermore, in British Specification Nos. 588043 and 1310683, there is described a writing pad comprising electrical supply and sensing circuits and a pair of sheets one of which has a resistive circuit, which sheets are moved into contact with one another by a writing implement whereby electrical potentials are applied to the surfaces and output potentials related to the position at which the two sheets contact one another are generated.
In U.S. Pat. No. 3,885,097, there is described a writing pad having two spaced apart sheets of resistive material which sheets are spaced apart by a mechanical separator such as a woven nylon cloth to prevent contact between the sheets when an operator's hand rests on the top sheet.
It is found that such writing pads suffer from the disadvantage that either electrical contact is made between the two sheets if an operator's hand is laid on the top sheet, or, alternately, effective electrical contact is not made between the two sheets throughout the whole length of a writing stroke.